The proposed series of studies examines intellectual development from the point of view of Piaget's theory. Central to that theory is the view that, in the first six months of life, "out of sight, out of mind" captures the sense in which infants are aware of objects. In the next six-plus months, infants increasingly come to be able to cope with absent objects, but they do this in a non-conceptual, an empirical, fashion. By 18 months, infants achieve a conception of objects as permanent, independent entities which exist in a more-or-less coherent spatio-temporal-causal framework. Recent studies of infants' tracking of moving objects suggest that 5 month old infants are able to keep objects in awareness on a conceptual basis. Such studies have been used to argue that Piaget's constructivist theory is in error and that much of the human species' awareness of the orderliness of the world is in-born. There are many methodological problems in these recent studies. I propose to do a tracking study which will more adequately assess whether the facts are in accord with these recent claims or with Piaget's theory. If the outcome of the study supports Piaget's views, then a number of studies will be conducted which will attempt to amplify Piaget's stage account of how object knowledge develops. If the study does not support Piaget's theory, then a number of studies will be carried out to clarify the nature of the relation between development in the first six months of life and that of the later phases of infancy.